The present invention relates to adhesive constructions and methods for manufacturing and using such constructions. In preferred applications, the invention particularly concerns adhesive constructions from which a label, cover or other adhesive component, can be applied from a release liner, in an effective and convenient manner.
In general, in many industries adhesive constructions are applied using high speed dispensing equipment, from a roll of individual constructions. The roll generally comprises individual elements in a line or column, adhered to a release liner, During an application process, the adhesive constructions or elements are sequentially stripped from the release liner and are applied to a package or other substrate on which such a construction is desired. Arrangements of this type are described, for example, in U.S. Pat. Nos. 5,351,426 and 4,661,189, the complete disclosures of which are incorporated herein by reference.
Adhesive constructions can be used in a variety of applications. For example, they may be used as labels or as covers. In other instances they may be used as components in larger systems, for example as a layer in a laminate.
An adhesive construction is provided. The adhesive construction involves a flexible substrate having a selected adhesive pattern, of pressure sensitive adhesive, on at least one side thereof. The selected adhesive pattern of pressure sensitive adhesive preferably includes at least a first adhesive field and a second adhesive field. In preferred constructions: the first adhesive field is a discontinuous pattern of adhesive with adhesive covering no more than 80% of an area of the portion of the first side of the flexible substrate defined by the first adhesive field, the area of that portion of the first side of the flexible substrate defined by the 80% adhesive field preferably being at least 10 square millimeters (sq. mm.), typically at least 30 sq. mm.; and, the second adhesive field preferably covers at least 80% (typically at least 90%) of an area of a portion of the first side of the flexible substrate defined by the second adhesive field; the area of the portion of the first side of the flexible substrate defined by the second adhesive field being at least 10 sq. mm., typically at least 30 sq. mm. Preferably there is more adhesive and more surface coverage, per unit area, in the second adhesive field than in the first adhesive field.
Adhesive constructions as defined herein may have still further adhesive fields thereon, as long as (preferably) the first and second adhesive fields are present.
In preferred adhesive constructions according to the present invention, the first and second portions of the selected adhesive pattern are preferably defined (respectively) by an outer perimeter adhesive field; and, an inner adhesive field. The preferred outer perimeter adhesive field is arranged along (or to border) a perimeter edge or edge portion of the flexible substrate. In such preferred embodiments, the inner adhesive field is completely surrounded or circumscribed by the outer perimeter adhesive field. In general, as described above, there is a higher amount of adhesive or higher coverage of flexible substrate surface by adhesive, in the region of the inner adhesive field, than in the region of the outer perimeter adhesive field. Preferred arrangements and amounts of coverage, are described.
In certain preferred arrangements, there is also provided an adhesive-free region on the flexible substrate. Preferably the adhesive-free region comprises an inner adhesive-free region completely surrounded or circumscribed by an inner (or second) adhesive field. In selected embodiments, the adhesive-free region is substantially transparent.
The adhesive construction will typically include, during a portion of its life prior to application to a package or other substrate, a release liner secured to the flexible substrate with the defined adhesive fields therebetween. The release liner generally would comprise a silicone release layer, to facilitate the separation of the release liner from the flexible substrate, during a labeling or covering operation, i.e., an application process, so that the flexible substrate could then be adhered to an appropriate package or other substrate.
Methods of preparing preferred adhesive constructions according to the present invention are provided. In general, the methods include: applying adhesive to create the different pressure sensitive adhesive fields defined; and, conducting appropriate die cutting and waste material stripping operations to achieve the generation of the individual adhesive constructions secured to a common release liner. In general, preferred die cutting operations will be conducted such that die cutting: is through a layer of laminate which will eventually become the flexible substrate of the adhesive construction; and, is in overlap only with adhesive in the first type of adhesive field, and thus in a pattern surrounding or circumscribing adhesive in the second type of adhesive field.
Preferred methods include applying adhesive to create a first, (for example outer perimeter) adhesive field and a second (for example inner) adhesive field by utilizing a printing approach, typically a dot screen printing approach, in which more adhesive is applied to the region that will become the second (inner) adhesive field than is applied to the region which will become the first (outer) perimeter adhesive field. This can be accomplished for example, by varying the number of dots or weight (wt.) of adhesive per unit area.
In typical manufacturing operations, a two layer laminate is prepared comprising two flexible webs secured to one another by adhesive. One of the flexible webs would comprise a release liner layer, and the other would comprise a flexible substrate web or layer that, when die cut, would form the flexible substrates of individual adhesive constructions for generation of the preferred constructions as characterized. The adhesive pattern between the two webs would typically have two regions: a region of adhesive in a concentration that, after a die cutting operation, would form the first (outer) perimeter adhesive field; and, a region of higher adhesive concentration which, after the die cutting operation, would form the second (inner) adhesive field. In preferred constructions, the adhesive fields of the laminate are organized such that during a die cutting operation, die cutting of the flexible substrate web only occurs in overlap with regions of lower adhesive concentration.